Alkali silica reaction (ASR) still has the potential to severely damage the Bureau of Reclamation's (Reclamation) concrete structures. ASR is a form of concrete deterioration caused by a reaction between alkalies in the cement used in concrete and certain types of aggregates. The reaction was discovered in the 1930s, and methods were developed to prevent the reaction from damaging concrete structures. Those methods were principally to limit the amount of alakalies in the cement used in the concrete and to use nonreactivce aggregates.
However, these methods are no longer as effective as they were once considered. This is due to a couple of factors - the lack of economically available high-quality aggregate sources and the increase in alkali content in cement due to energy use issues. It seems ASR will always be around some areas of the country and will likely start to be more of a problem in the foreseeable future. Fortunately, a solution has been found that has the potential to reduce or eliminate ASR in new concrete structures. Lithium is that solution. In fact, we had two projects within the last year in which reactive aggregates were proposed for use in the concrete mixture that used lithium to mitigate the reaction.
When added to concrete, lithium chemically mitigates the formation of ASR, thus maintaining durability and increasing service life. One concern with using lithium to mitigate ASR is leaching of the lithium by water out of the concrete. If the lithium were to leach out of the concrete, over time the concrete would be at risk of suffering from ASR, then expanding and developing cracks. Knowing the long-term leaching characteristics would help us determine if lithium is a viable solution for ASR mitigation for concrete exposed to water.
Need and Benefit
Funding for these tasks would help in the decision process of whether to allow the use of lithium in a water containing structure. This knowledge is required in order for us to design our structures that are located in areas with ASR problems.
There are substantial questions about the effectiveness of the use of lithium in concrete or concrete repair applications to mitigate ASR.
The findings of this scoping study will be used to:
*Determine the previous applications of lithium to mitigate ASR
*Determine if lithium is potentially effective for use in hydraulic concrete applications and if industry has any experience in this area
* Determine if previous work addresses long-term lithium viability for use in hydraulic applications to arrest ASR
*Determine if there are applications within Reclamation that are worthy of a research effort
* Determine if there are concrete durability models capable of taking short-term laboratory results and validating long-term durability predictions
Develop a plan to perform laboratory research.
This information was last updated on April 25, 2014
Contact the Research and Development Office with questions or comments about this page